In existing tungsten halogen lamp bases, the top of the base typically terminates at the press-sealed end of the lamp capsule below the area of the lamp where the press-sealed portion joins the major diameter of the capsule's bulb portion. Thus, in the prior art, the only portion of the capsule typically enclosed within the ceramic base is a relatively large part of the capsule's press-sealed portion. Lamps that generally depict capsule support using such an arrangement are shown in U.S. Pat. Nos. 3,431,540 (Kopelman et al.) and 4,243,907 (Kohl et al.), both assigned to the present assignee. Reference may also be made to the "IES Lighting Handbook," 4th edition, published by the Illuminating Engineering Society (New York, N.Y.), at page 8-4, wherein several types of bases, including prefocus and bipost, are illustrated. When used in conjunction with tungsten halogen lamps, such lamps typically operate at color temperatures on the order of 3200.degree. K. By way of example, one type of lamp presently available from the assignee of this invention is classified as an EGT type lamp, which operates at 1000 watts, 120 volts, provides a nominal output (lumens) of 28,000, possesses an average rated life of about 200 hours, and employs a C-13D filament structure within its glass envelope. Examples of this and other filament structures capable of being utilized in lamps of the type defined herein are illustrated on page 8-3 (and described on pages 8-1 and 8-2 of the aforementioned "IES Lighting Handbook."
The problem with such existing designs is that breakage of the capsule at the press-seal portion may occur during shipment as well as during installation of these lamps in their respective fixtures. Breakage occasionally occurs during shipment because fixtures utilizing these lamps are typically shipped with the lamps therein. With existing tungsten halogen lamp bases, it has been found that the lamps break in the press area under typical applied force values in the range of only ten to twenty inch-pounds.